NSEC Executive Committee Member
Professor
Departments of Physics and Applied Physics
horst@phys.columbia.edu

Research into the electrical conductivity of single molecules continues to be very challenging. Apart from the obvious requirements for very small leads and very small contact spacings to match the dimensions of a molecule, there exists presently no means to monitor conduction, while independently verifying the presence or absence of a molecule between the nano-fabricated contacts. Yet, such a cross correlation is of extraordinary importance to convince ourselves that the conductance features indeed arise from a single molecule in a particular configuration between the conducts. Metal contacts are generally large, thereby obscuring access to the molecule by standard scanning probe microscopies. We are developing techniques to create ultra thin metal contacts, separated by nano-scale gaps as well as strategies to locate specific contacts in order to detect the presence of a molecule in a specific gap by scanning probe microscopy and correlate it with in-situ conductance data. The simultaneous “visual” observation of a molecule between contacts and a characteristic feature in conductance is our goal.

Selected Publications

• G. A. Csathy, J.S. Xia., C. L. Vincente, E.D. Adams, N.S. Sullivan, H.L. Stormer, D.C. Tsui, L.N. Pfeiffer, and K.W. West, “ Tilt induced localization and delocalization in the second Landau level”, Phys. Rev. Lett, 94, 146801/1-4 (2005).
• G. Gervais, H. L. Stormer, D. C. Tsui, P. L. Kuhns, W. G. Moulton, A. P. Reyes, L. N. Pfeiffer, K. W. Baldwin, and K. W. West, “ Evidence for Skyrmion Crystallization from NMR Relaxation Experiments”, Phys. Rev. Lett. 94, 196803/1-4 (2005).
• W. Pan, J.S. Xia, H.L. Stormer, D.C. Tsui, C.L. Vicente, E.D. Adams, N.S. Sullivan, L.N. Pfeiffer, K.W. Baldwin, and K.W. West, “ Quantization of the diagonal resistance: Density gradients and the empirical resistance rule in a 2D system”, Phys. Rev. Lett. 95, 066808/1-4 (2005).
• Y. Zhang, Y.-W. Tan, H.L. Stormer, P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene”, Nature 438, 201-204 (2005).
• Y. Zhang, Z. Jiang, J. P. Small, M. S. Purewal, Y.-W. Tan, M. Fazlollahi, J. D. Chudow, J. A. Jaszczak, H. L. Stormer and P. Kim, “Landau Level Splitting in Graphene in High Magnetic Field”, Phys. Rev. Lett. 96, 136806/1-4 (2006).